Method of making blanking die assemblies



March 1, 1960 D. H. Dl JLEBOHN ET AL 2,927,190

METHOD OF MAKING BLANKING DIE ASSEMBLIES Filed March 51, 1958 2 Sheets-Sheet 1 DAVID H. DULEBOHN ,6 Thoma LTwm uwT 615mm 5 Wsunss M fj/ M v March 1, 19 D. H. DULEBOHN ET AL 2,927,190

METHOD OF MAKING BLANKING DIE ASSEMBLIES Fil ed March 51, 1958 2 Sheets-Sheet 2 THO/141454. TUBA 62007 ji'FPfiH/V 5. Wf/V/VES ;METHOD OF MAKING BLANKING DIE ASSEMBLIES DavidH. Dulebolm, Thomas L. Turnquist, and Stephen -B. Wennes, Minneapolis, Mime, assignors, to Dayton Rogers Manufacturing Co., Minneapolis, Minn a corporation of Minnesota Application March 31, 1958', Serial No. 725,205

6 Claims. (Cl. 219-69) This invention relates to a method of making blanking die assemblies.

In the art of making blanking die assemblies it has been common practice in the past to first produce the die by scribing and rough sawing the opening in the die blank and then filing off the finishing stock to the scribed pattern laid out on the blank. This hand filing in the hole is extremely time-consuming and tedious. Before the die is carburized and hardened, holes are drilled along the edges of the die for subsequently mounting stock guides or spacer strips for supporting the nest plate. Hardening of the ,die frequently causes distortion in the shape of the die and therefore the die must be subsequently straightened by a time-consuming and costly process. The die is then used as a template for scribing on a metal blank the configuration of the punch which is to be made from the blank. The punch blank is then rough sawed and filed to fit tightly in the dieopening and then the punch is sheared into the hard die, whereuponthe metal of the soft punch is broached back at the edges thereof. While the punch remains partially inserted in the die opening, a nest plate blank is clamped, to the die and holes are drilled into the nest plate blank in alignment with the iOlfiS in the die, and a number of aligned holes are also drilled in the punch and nest plate blank. Subsequently the punch is removed from the die andfiled to the proper size. The broached metal on the soft punch is used as a gauge of the point at which filing should be stopped. Subsequently the punch is hardened and then the nest plate blank isdoweled at the holes previously formedto the punch and die. Application of pressure on the. punch causes blanking of the nest plate blank, and subsequently the die and nest plateare assembled with the stock guides as by rivets.

It should be particularly noted that this previous method involves a. considerable amount of hand filing in the die opening which may be of an intricate shape. Furthermore, the straighteningof adie distorted during heat treating is a difiicultand extremely time-consuming operation.

With these comments in mind, it is to, the elimination of these and other disadvantages inthese known methods .that our-invention is directed, along with the provision of other novel procedures.

An object of ourinvention is to provide a novel and inexpensive method ofv producing temporary blanking die assemblies.

Another object of our invention isthe provision of a new and improved method of producing a temporary blanking die and punch wherein the amount of machining and accurate hand filing of the parts is at an absolute minimum and wherein such filing is done on outside surfaces of a single element.

A further object of our invention is to provide a novel and improved method of making a temporary blanking die wherein thedie opening is formed by arc'disintegration. and wherein the nest-plate blank. is first utilized'for locating the electrode and die relative to each otherin 2,927,196 Patented Mar. 1, $66

the arc disintegrating process and is subsequently utilized novel and improved method of making a temporary blanking die which eliminates the necessity of straightening the die after heat'treating thereof.

hese and other objects and advantages of our invention will more fully appear from the following description :made, in connection with the accompanying drawings wherein like reference characters refer to the same parts throughout the several views and in which:

.Figs. 1-9 show the successive steps of carrying out the method of making temporary blanking die assemblies, and more specifically:

.Fig. l is a perspective view of the sandwiched blanks for producing the punch and electrode;

Fig. 2 is a perspective view ofthe sandwiched punch and electrode;

Fig. 3 is a perspective view of the sandwiched punch andelectrode in stacked relation with the nest plate blank and die blank for producing dowel holes in first and second patterns;

Fig. 4 is a perspective view of the sandwiched punch and electrode doweled to the die blank for marking on the blankthe area thereof to be removed;

Fig. 5 is a transverse section view through the die blank after the die opening has been rough-sawed therein;

Fig. 6 is a vertical section view of the electrode nest late, blank and die blank doweled together for alignment cise configuration of the punch;

.Fig. ,8 is an end elevation view, partly insection, of the .nest plate blank sandwiched between and doweled to the punch and die forblanking the opening in the nest plate;

Fig. 9 is a perspective view of the die and nest plate assembled for blanking operation;

Figs. 10,11 and .12 are diagrammatic perspective views showing another embodiment of the invention; and

Fig. 13 is a diagrammatic perspective view of still another embodiment of the invention.

The method of forming the temporary blanking die assembly includes the steps of securing a steel punch blank it} in face-to'face relation with a thin brass electrode blank til by such means as to temporarily but securely hold these blanks in sandwiched relation. The blanks 10 and 11 may be secured together as by dowels 20a in the dowel holes 18, or on the alternative, the blanks may be secured together as by soldering. The shape of the punch to be formed is scribed onto one of the blanks as at 12. It should be understood that the inneropposed surfaces of the blanks 10 and 11 and the outer surfaces are finished.

The marginal material of the blanks 10 and 11, outside of the scribed line 12, is then removed as by hand sawin close to the line 12 and the perimeter is machine or hand filed to produce the punch-electrode sandwich 13 substantially identical in peripheral dimensions and shape to thepunch 14. In certain cases, it may be desirable to make the electrode slightly smaller than the punch, depending on thickness of material to be blanked by the die.

The securing of the punch and electrode blanks together, and then removing the marginal material of both blanks in one operation is a substantial improvement over past procedures of filing of several parts. It should be noted that the electrode may be constructed of relatively thin stock, for reasons that will more fully appear, and it will be readily understood that less filing is required when the stock employed is thin. V

The sandwich 13 is then laid upon a nest plate blank, or alignment plate 16 which overlies a steel die blank 17. The nest plate blank is also constructed of steel, but is considerably thinner than the die blank 17. The punch-electrode sandwich 13, the nest plate blank 16 and the die blank 17 are then clamped together in the position shown in Fig. 3 and a plurality of dowel holes 18a and 13b are then produced in the nest plate blank 16 and die blank 17. It is preferred that these dowel holes be arranged in an asymmetric pattern so that after these parts are disassembled, they may be reassembled in only one arrangement. While the-sandwich and blanks remain clamped in the position shown in Fig. 3, a plurality of dowel holes 19 are produced, as by drilling, in a second pattern adjacent the opposite edge portions of the nest plate blank 16 and the die blank 17. It will be noted that the second pattern of dowel holes 19 lie outside of the area covered by the punch-electrode sandwich 13.

When the dowel holes 18a, 18b and 19 have been produced, the nest plate blank 16 is removed from the sandwich 13 and die blank 17, and the sandwich 13 is laid directly upon the die blank 17 and is secured in a predetermined position thereon by means of a plurality of dowels 20 which are inserted through the aligned dowel holes 18a and 18b and the sandwich 13 and die blank 17, respectively. The steel punch 14 comprising one of the laminations of the sandwich 13 is then used as a template and a line is then scribed on the die blank 17 around the periphery of the punch 14. The scribed line, indicated by numeral 21, defines the area of the die blank 17 which is to be removed thereby forming a punch-receiving opening in the die blank. After the line 21 is scribed, the dowels 20 will be removed and the punch 14 and electrode 15 are then separated. The steel punch 14 will then be carburized and hardened so as to be ready for use as a punch in a blanking operation.

An Opening 22 (see Fig. is then produced, as by hand sawing,-in the die blank 17 so that the periphery of the opening conforms generally to the configuration of the scribed line, 21. By sawing inside of the scribed line 21 and at an oblique angle with the upper marked surface 24, the resulting inside surfaces 23 are disposed at an angle of approximately ten degrees from the normal with respect to the upper and lower surfaces 24 and 25 of the die blank. The opening 22, at the upper surface 24, is slightly smaller than the area circumscribed by the line 21; and the opening 22 at the lower surface 25, is slightly larger than the area circumscribed by the line 21. It will therefore be seen that finishing stock remains between the edge 23 of the opening 22 and the scribed line 21 at the upper surface 24 of the die blank 17.

While the die blank is in this unfinished state and before the edge of the die opening is accurately produced at the scribed line 21, the die blank is hardened by heat treating. Any slight distortion of the die blank which occurs during heat treating is of little consequence because the edge of the die opening is subsequently formed.

The cutting edge of the die opening is then produced by removing finishing stock in a process of arc disintegration. To this end, the electrode 15 is applied to the quill adapter 26 of a high frequency are disintegrating machine which is of common knowledge to the persons skilled in arts of metal working. It has been found successful to employ such a machine as is known as the Elox Arc Disintegrating Machine, produced and sold by the Elox Corporation of Michigan, Clawson, Michigan, which incorporates a high frequency electronic generator '27 producing discharges at the electrode 15 at a rate of 20,000 to millions per second and at a voltage which may be 50 volts. As shown somewhat diagrammatically in Fig. 6, the machine provides a tub or receptacle 28 containing an oil bath 29, the surface of which is indicated at 29a. Suitable mounting means are provided in the tub 28 for supporting the die blank 17 and in the form shown, such means comprise metal mounting blocks 30 supporting the die blank 17 and being tapped and threaded at 30a for receiving a securing screw 31 for a clamping element 32 which holds the die blank 17 downwardly against the block 30. It will be noted in the drawings that the die blank 17 must be placed in inverted position in the oil bath and on the mounting blocks. The generator 27 is connected as by conductors 33 and 34 to the quill adapter 26 and tub 28, thereby providing a high frequency electric potential between the die blank 17 and brass electrode 15.

Before the die blank 17 is tightly secured by the clamping elements 32, the nest plate blank 16 is sandwiched between and doweled to the electrode 15 and the die blank 17 as by dowels 20 and 35 in the aligned dowel holes of the nest blank 16 and die blank 17 respectively. The electrode 15 is thereby precisely aligned with the original scribed line 21. The aligned electrode 15 and die blank 17 are then clamped to prevent any further lateral shifting thereof. The dowels 20 and 35 are removed and the nest plate blank is also removed to permit the electrode 15 to move downwardly.

With high frequency electric potential applied between the die blank 17 and electrode 15, the quill adapter 26 is moved downwardly to move the electrode 15 through the opening 22 and into close proximity with the periphery of opening 22. As the electrode 15 passes downwardly into the dotted position B thereof the finish stock is completely removed by are disintegration to form surface 230 at the scribed line 21. The opening 22 at the surface 24 conforms precisely in size and configuration to the shape of punch 14. The cutting edge of the die has the original precision of the electrode and has a degree of smoothness that enables excellent stamping production.

It should be noted that because of the angular orientation of the opening-defining surface 23, the disintegration process removes material through only a fraction of the thickness of the die blank. As best seen in Fig. 7, only sufficient stock has been removed to form the surface 230. The thickness of stock removed (which is equal to the width of surface 23a) by arc disintegration is important because, ordinarily, the electrode 15 must be approximately three times as thick as the thickness of stock to be removed. It is desired to keep the thickness of the electrode 15 as thin as possible because the electrode-punch sandwich 13 must be hand filed in many cases of intricate blanking patterns.

Subsequently the nest plate blank is then reapplied to the completed die 17a and is aligned therewith by the dowels 35 in the holes 19. The punch 14 is then applied onto the nest plate blank 16 and is aligned with the opening 22 in the die 17a by dowels 20 extending through the apertures 18 and 18a in the punch 14 and blank 16. By any suitable means the punch 14 is then driven through the nest plate blank 16 to shear an opening 36 therein, identical in size and configuration to the punch. The nest plate 16 will then be secured to the die 17 as by rivets 37 extending through the holes 19 of the nest plate 16 and die 17a. Of course stock guides or spacer strips 38 will be inserted between the nest plate the die EtO allow for insertion of stock S .therebeitween.

.In the embodiment of .the invention shown in Figs. 10, 11 and 12, the punch and die are of the type employed for blanking small stampings and the like and are adapted to be set up in a semi permanent condition in a punch press machine.

In the formation of 'the matching punch and die, a blank or piece of bar stock 40, from which the punch is to be formed, is secured to an electrode blank 41 in "the punch and electrode blanks have been secured together, to form apunch-electrode sandwich, indicated in general by the numeral 42, the punch and electrode blanks 40 and 41 are machined or otherwiseshaped into the size and'configuration of the part to be blanked. ,In the embodiment shown in the drawings, the ;part tobe :blan'ked is circular, and it will be seen that the punch welectrode sandwich '42 is secured inthe chuck C of alathe ;and is being turned down to a circular shape by the cut- .ting tool T. Therefore it will be seen that by securing the electrode and punch blanks together, only one machining or similar operation is necessary to shape the punch and electrode substantially identical to each other :and to the size and configuration of the part to be wblanked. When the punch and electrode have been xmachined to the proper size and configuration, means,

:suchas the notch -43,-are formed in the punch 40a to facilitate securing ofthe punch in the ram of a punch press.

While the punch 40a and the electrode 41a are secured together, the punch electrode sandwich is secured in the quill adapter Q of the. Elox Arc Disintegrating Machine previously described. If the part to be blanked by the punch and die assembly being formed is of a symmetri eal shape, .such as in the present situation wherein the blank 44 is placed in a receptacleR containing an oil bath or coolant B in the manner previously set forth. A number of holes 440 may have been drilled in the die blank 44 to reduce the amount of material which is to be .removed by are disintegration. After the high frequency generator G is attached to the quill adapter Q and receptacle R so as to apply a high frequency potential difference between die blank 44 and electrode 41a, the electrode 41a is moved toward and into and through the die blank 44 so as to cause, by are disintegration of the die blank 44, production of a die opening in the blank 44. As previously described, it is preferable that the die blank be hardened before the die opening is formed therein.

After the opening has been produced in the die blank 44, the electrode-punch sandwich is moved from the quill adapter Q and the electrode 41a and punch 40a are separated from each other and subsequently the punch 46a is hardened, at which time the punch and die are ready for application into a punch press machine for a blanking operation.

The embodiment shown in Fig. 13 relates to the production of a punch and die for blanking parts which are asymmetrical in shape. The steps described in connection with Figs. and ll will be followed, wherein the punch blank and electrode blank are secured together as by braising and thereafter, the punch-electrode sandwich is machined, hand filed, or otherwise formed in a single operation so that both the blanking punch 50 and the electrode 51 have substantially identical configurations. In the present embodiment wherein the part to be produced is asymmetrical the electrode 51 must be separated from the punch 50 and inverted before being applied by itself onto the quill adapter of the arc disintethe opening therein.

.grating machine. Means such as tapped aperture 51a through the die blank'52 to decrease the quantity of 10 .face-to-face and conducting relation'as by brazing. When a metal which must be removed from the die blank to formthe die opening therein. When the punch and die .are assembled into a punch press machine fora blanking operation," the die will be inverted from the position shown in Fig. 13 so as to match the shape of thepunch. It will, of course, be understood that various changes maybe made in the form, detail, arrangement andproportion of the parts ithout departing from thescope of myinvention which consists of the matter described herein and set forth in the appended claims.

What is claimed is:

1 vIn the art of making from a metal blank, a blanking die for use with a preformed punch, the method steps consisting in producing a thin electrode shaped substantiallyidenticalto the punch, marking on one surface of thedie blank the pattern of the punch, cutting through the die blank at an oblique angle and inside of the marking at the marked surface and outside of the marking at the other surface and progressively cutting at the oblique angle around the marked pattern to formin the die blank an openingsmaller than the punch at the marked surface and largerthan the punch at the other surface, aligning the electrode with the pattern marking of .the dieblank and applying high frequency electric potential between the electrode and blank and then moving the electrode in a coolantand into the larger end of the die blank opening and through the die blank to cause by are disintegration of the blank, enlargement of the opening adjacent the marked surface and production of a cutting edge identical in configuration to the marking and punch,

whereby a thin electrode, which may be easily produced, may be utilized whereas enlargement of the die blank opening is necessary through only a fraction of the thickness of the die blank. I

2. In the art of producing a temporary blanking die assembly for blanking parts having a certain shape, the method steps consisting in producing a punch and an electrode shaped substantially identically to the part to be blanked, producing a plurality of dowel holes in a first pattern in the punch and electrode and also in a die blank, 'doweling the-punch to the die blank and marking on the die blank around the punch to define the area of the die blank to be removed, producing in the die blank and outside said area a plurality of dowel holes in a second pattern, producing in a nest plate blank a plurality of dowel holes in the precise arrangement of all of the holes in the die blank and then cutting through the die blank at an oblique angle and inside of the marking at the marked surface and outside of the marking at the other surface and progressively cutting at the oblique angle around the marked pattern to form in the die blank an opening smaller than the punch at the marked surface and larger than the punch at the other surface, sandwiching the nest plate blank between and doweling the nest plate blank to the die blank and the electrode to align the electrode with the marking on the die blank, securing the electrode and die blank in the aligned relation and removing the nest plate blank and applying high frequency electric potential between the electrode and the die blank and then moving the electrode in a coolant into the larger end of the die blank opening and through the die blank to cause by are disintegration of the blank enlargement of the opening adjacent the marked surface and production of a cutting edge identical in configuration to the marking and punch, producing a punch-receiving opening in the nest plate blank and securing the nest plate to the die at the second pattern of dowel holes, whereby the nest plate blank is utilized in aligning the I electrode with the marking on the die blank so that enlargement of the die blank is necessary through only a fraction of the thickness of the die blank.

3. In the art of producing a temporary blanking die assembly for blanking parts having a certain shape, the method steps consisting in producing a punch and an electrode shaped substantially identically to the parts to be blanked, producing a plurality of dowel holes in a first pattern in the punch and electrode and also in the die blank, doweling the punch to the die blank and marking on the die blank around the punch to define the area of the die blank to be removed, producing in'the die blank and outside of said area a plurality of dowel holes in a second pattern, producing in a nest plate blank a plurality of dowel holes in the precise arrangement of all of the holes in the die blank, producing in the die blank an opening slightly inwardly from the marking thereon and following the peripheral configuration of the marking, and then sandwiching the nest plate blank between and doweling the nest plate blank to the die blank and the electrode to align the electrode with the marking on the die blank, securing the electrode and die blank in the aligned relation and removing the nest plate blank and applynig high frequency electric potential between the electrode and the die blank and then moving the electrode in a coolant and toward and into the die blank to cause by arc disintegration enlargement of the opening in the die blank to the precise shape of the punch, sandwiching the nest plate blank between and doweling the nest plate blank to the punch and die and then applying pressure on the punch to produce a punch-receiving opening in the nest plate blank, and securing the nest plate to the die with the dowel holes thereof in alignment, whereby the nest plate blank is utilized in aligning the electrode with the. marking on the die blank and is subsequently utilized in aligning the punch and die opening in forming the opening in the nest plate which is thereafter employed for aligning the punch and die opening in a blanking operation.

4. In the art of producing a blanking die assembly for blanking parts having a certain pattern, the method steps consisting in securing a punch blank and an electrode blank together in face-to-face relation, removing in the same operation outside portions of both blanks to form a punch and an electrode substantially identical in shape to the pattern, securing the electrode and the die blank in confronting relation With each other and immersed in a liquid coolant and applying a high frequency electric potential between the electrode and die blank and then producing relative convergent movement between the electrode and die blank into close proximity with each other to cause arc disintegration of the blank and production therein of an opening having a peripheral cutting edge shaped substantially identical to the punch. 1

5. In the art of producing a blanking die assembly for blanking parts having a symmetrical pattern, the method steps consisting in securing a punch blank and an electrode blank together in face-to-face and conducting relation to produce an integral sandwich, removing in the same operation outside portions of both blanks in the sandwich to form a punch and an electrode substantially identical in shape to the pattern, securing a die blank and the punch of the punch-electrode sandwich in alignment with each other and with the electrode and die blank in confronting relation with each other and immersed in a liquid coolant and applying a high frequency electric potential between the sandwich and the die blank and then producing relative convergent movement of the punch-electrode sandwich and the die blank to cause arc disintegration of the die blank and the formation in the die blank of an opening having a peripheral cutting edge shaped substantially identical to the punch, and separating subsequent to the arc disintegration the punch and electrode from each other.

6. In the art of producing a blanking die assembly for blanking parts having an asymmetrical pattern, the method steps consisting in securing a punch blank and an electrode blank together in face-to-face relation, to produce an integral sandwich, removing in the same operation outside portions of both blanks in the sandwich to form a punch and an electrode substantially identical in shape to the pattern, separating the electrode and punch, securing the electrode and the die blank in confronting relation with each other, but with the electrode inverted with respect to the orientation of the punch when the same is to be subsequently used with the die in a blanking operation, applying a high frequency electric potential between the electrode and die blank and then moving the electrode in a liquid coolant and completely through the die blank to cause arc disintegration of the blank and production therein of an opening having a peripheral cutting edge shaped substantially identical to the punch.

References Cited in the file of this patent UNITED STATES PATENTS Griffith Oct. 2, 1956 Matulaitis July 23, 1957 

